PBAW devices are successfully used in wireless communication systems as a result of their small size and low insertion loss provided by resonator-type structures, built on piezoelectric substrates with high electromechanical coupling factors.
It may be generally desirable for the PBAW device to have a smooth frequency response over a relatively large range of frequencies. However, in some cases, a PBAW device may have “spurious” modes where the frequency response of the PBAW device becomes distorted. In these cases, the PBAW device may have a relatively increased or decreased frequency response for a relatively narrow frequency band. These PBAW devices may be difficult to use, because the spurious modes may produce unpredictable results, or significant deviations, over relatively narrow frequency ranges.